class Solution
{
public:
    int countOrders(int n)
    {
        // 由数学直接得到表达式 (2n)!/2^n
        long long result = 1;
        for (int i = 1; i <= n; ++i)
        {
            result *= (2 * i - 1) * i;
            result %= 1000000007LL;
        }
        return result;
    }
};